Some consumers are believed to show a preference for thickened cleaning or brightening compositions, and thickened cleaners are useful, for example, as oven cleaners, paint strippers and toilet bowl cleaners as they can be more readily positioned upon the area being cleaned. Additives for thickeners have included natural gums such as guar and locust bean extract, starches and cellulose and their derivatives.
Polymeric thickeners for acidic surfactant compositions are described by U.S. Pat. No. 4,552,685, issued Nov. 12, 1985, inventors Kernstock et al. and by U.S. Pat. No. 4,529,773, issued July 16, 1985, inventors Witiak et al. However, these acidic-thickened solutions require high levels of surfactant in order to solubilize the copolymers and they have higher viscosities at pH 7 than when the pH is lowered into the acidic region.
U.S. Pat. No. 4,515,929, issued May 7, 1985, inventor Tang and No. 4,552,682, issued Nov. 12, 1985, inventors Black and Tang, teach solid organic peroxide that is dispersed with a surfactant and thus is in emulsion or suspension in a thickened aqueous phase. Thickeners for the aqueous phase can be such as polyvinylalcohol, polyacrylic acid or polyvinylpyrrolidone. The organic peroxide is thus a discontinuous phase. Earlier, U.S. Pat. No. 4,130,501, issued Dec. 19, 1978, inventors Lutz and Cohen, disclosed that liquid bleaches based upon hydrogen peroxide were not stably thickened with polyvinylpyrrolidone.